The Challenges of Obtaining Accurate Measurements with Decreasing VOC Levels

By Jeremy Powers, Dr. Brij Mohal, Selby Brannon

Long ago, scientists stopped measuring the denier of hair with yard sticks and triple beam balances. Currently, the gas chromatograph (GC) analysis methods used, in the art, to measure volatile organic compounds (VOC) in colorants follow equally antiquated reasoning. Despite the interlaboratory precision that these methods may exhibit, they are frequently inaccurate due to a dependency upon the chemistry of coatings samples investigated.

Nevertheless, numerous governing bodies—domestic and worldwide—attempt to regulate the amount of VOC in coatings dispersions without the presence of a truly accu-rate method. The global trend toward lower VOC in coatings markets, and the liability therein, are leading scientists to evaluate several methods for gas chromatography to accurately determine the VOC of coatings dispersions. In the United States, the Federal Trade Commission (FTC) is cracking down on false advertising as it relates to low- or no-VOC finished paints.

Two top U.S. coatings companies faced charges from the FTC in October 2012 on misleading consumers that their paints were free of VOC.¹ Unfortunately, current methods for VOC analysis such as EPA 24, ISO 11890-2, ISO 17895, and ASTM D6886 are dependent upon sample, solvent, concentration, and GC column, each of which can contribute to inaccuracies.

The focus of this article is to demonstrate that gas chromatography mass spectroscopy head-space (GC-MS HS) analysis is preferable after quantitative screening methods have been applied. No current method is perfect for all requirements; therefore, verification methods for VOC results are reviewed and the degree of probable success evaluated.